title: OTULIN restricts Met1-linked ubiquitination to control innate immune signaling.
abstract: Conjugation of Met1-linked polyubiquitin (Met1-Ub) by the linear ubiquitin chain assembly complex (LUBAC) is an important regulatory modification in innate immune signaling. So far, only few Met1-Ub substrates have been described, and the regulatory mechanisms have remained elusive. We recently identified that the ovarian tumor (OTU) family deubiquitinase OTULIN specifically disassembles Met1-Ub. Here, we report that OTULIN is critical for limiting Met1-Ub accumulation after nucleotide-oligomerization domain-containing protein 2 (NOD2) stimulation, and that OTULIN depletion augments signaling downstream of NOD2. Affinity purification of Met1-Ub followed by quantitative proteomics uncovered RIPK2 as the predominant NOD2-regulated substrate. Accordingly, Met1-Ub on RIPK2 was largely inhibited by overexpressing OTULIN and was increased by OTULIN depletion. Intriguingly, OTULIN-depleted cells spontaneously accumulated Met1-Ub on LUBAC components, and NOD2 or TNFR1 stimulation led to extensive Met1-Ub accumulation on receptor complex components. We propose that OTULIN restricts Met1-Ub formation after immune receptor stimulation to prevent unwarranted proinflammatory signaling.
authors.affiliation: Department of Disease Biology, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Berthe Katrine
authors.initials: BK
authors.lastname: Fiil
authors.affiliation: Department of Disease Biology, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Rune Busk
authors.initials: RB
authors.lastname: Damgaard
authors.affiliation: Department of Proteomics Novo, Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Sebastian Alexander
authors.initials: SA
authors.lastname: Wagner
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
authors.forename: Kirstin
authors.initials: K
authors.lastname: Keusekotten
authors.affiliation: Department of Disease Biology, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Melanie
authors.initials: M
authors.lastname: Fritsch
authors.affiliation: Department of Disease Biology, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Simon
authors.initials: S
authors.lastname: Bekker-Jensen
authors.affiliation: Department of Disease Biology, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Mailand
authors.affiliation: Department of Proteomics Novo, Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Chunaram
authors.initials: C
authors.lastname: Choudhary
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
authors.forename: David
authors.initials: D
authors.lastname: Komander
authors.affiliation: Department of Disease Biology, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Mads
authors.initials: M
authors.lastname: Gyrd-Hansen
mesh_terms: D010450:Endopeptidases / Q000502:physiology*; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D007113:Immunity, Innate; D018836:Inflammation Mediators / Q000378:metabolism; D008715:Methionine / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D053473:Nod2 Signaling Adaptor Protein / Q000378:metabolism; D025941:Protein Interaction Mapping; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2 / Q000378:metabolism; D015398:Signal Transduction; D054875:Ubiquitination; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism
chemical_list: D018836:Inflammation Mediators; D016328:NF-kappa B; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D008715:Methionine; C506253:RIPK2 protein, human; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D010450:Endopeptidases; C582107:OTULIN protein, human